Anonymous US intelligence officials reportedly told the Washington Post that "newly analyzed information gathered by US intelligence agencies confirmed that on May 23, senior members of the UAE government discussed the plan and its implementation".

UAE Ambassador to the US Yousef al-Otaiba denied the report in a statement, saying it was "false", Al Jazeera Quoted the Post report.

"What is true is Qatar's behaviour". "Funding, supporting, and enabling extremists from the Taliban to Hamas and Qaddafi..." Inciting violence, encouraging radicalization, and undermining the stability of its neighbors.

Qatari Emir Tamim bin Hamad Al Thani was falsely quoted as praising Hamas and Hezbollah, as well as speaking positively about Iran and Israel - remarks that drew the ire of Saudi Arabia and the UAE, and were later used as justification for severing diplomatic ties with the tiny Gulf kingdom.

Still, four Arab states - the United Arab Emirates, Saudi Arabia, Egypt and Bahrain - cut diplomatic and trade ties with Qatar and issued a list of 13 demands.

A senior United Arab Emirates (UAE) official said worldwide monitoring was needed in the standoff between Qatar and its Arab neighbours, adding he saw signs that the pressure exerted on Doha "was working".

The Federal Bureau of Investigation was previously known to be working with Qatar to probe the hacking.

"Perhaps this will finally result in some movement".

With US spy agencies now apparently briefing against them, Qatar's antagonists may conclude US sympathy for their position is rapidly dwindling.

Several bankers, including two at Qatari institutions involved in the proposed deal, told Reuters that the refinancing had been indefinitely postponed as the crisis had deterred Gulf banks from doing new business with Qatar and tightened liquidity in the domestic Qatari money market.

"We need to be certain that Qatar, a state with $300 billion in reserves, is no longer an official or unofficial sponsor of jihadist and terrorist causes", he said, giving no further detail on the proposed monitoring.

While previous reports have cited United States officials claiming that Russian hackers were involved in the QNA incident, they were not explicitly tied to any of the four countries isolating Qatar.

"It's denial after denial after denial".

They say Qatar has supported many radical groups.

"So the failure, if you will, or at least temporary failure of Tillerson is not going to change unless there is a change of attitude on the part of the Emirates in particular".